The prices of rare-earth metals have tumbled from their June highs after China, a key refiner, resumed the import of ores from Myanmar in September but supply concerns continue to plague the market.

In mid-November, neodymium, an ingredient of permanent magnets used in electric vehicle motors, was traded at around $54 per kilogram, while dysprosium, which is added to improve permanent magnets’ heat resistance, was traded at around $230 per kilogram. Both values were 20% lower than their recent highs in June, and at their lowest points since April.

China’s Yunnan Province, which borders Myanmar, suspended imports of all resources, including rare-earth ores, from its neighbor in November 2018. It was thought that this move was a crackdown on the smuggling of rare-earth metals into China from mines in neighboring Kachin State and other places in Myanmar, where many Chinese were working.

Rare-earth ores mined in Myanmar contain high concentrations of dysprosium, which is mined in only limited areas in China. Myanmar had become an attractive source for Chinese refiners as its rare metals are traded at relatively low prices due to cheap labor and loose environmental protection.

The suspension of imports from Myanmar has pushed up dysprosium prices since the start of the year, paving the way for soaring rare-earth metal prices in May and June over speculation that China could announce a ban on imports. Rare-earth metal prices are particularly susceptible to movements in China’s market, given its small size and the country’s dominance.

But the suspension was abruptly lifted in late September and even now, traders have few clues as to the reasons behind China’s move. “I have no idea what is going on,” said Yutaka Kawasaki, general manager of Samwood, a Japanese trading house that deals in rare earth.

At the same time, the trade war between the U.S. and China has entered a “ceasefire,” easing supply in the market, which in turn led to a decline in prices. Although prices now appear to have flatlined, market players remain worried that China might halt imports again.

Myanmar is a close ally of China’s in its Belt and Road Initiative. The two countries have deepened relations, and China has taken Myanmar’s side when it came under fire from the international community over its treatment of the Rohingya Muslim minority.

Yet, China can’t afford to turn a blind eye to the smuggling. There is also speculation that Myanmar wants to improve the environmental protection of its own rare-earth mines, which may have led to some conflict with China.

“The supply of rare-earth metals to China could be stopped again,” said Yuji Tanamachi, president of IRuniverse, a Tokyo research company that focuses on the metal industry.

So far, China makes about half the number of electric vehicles and other new-energy vehicles globally. This means that demand for rare-earth metals used to make permanent magnets for motors is also growing.

China’s Ministry of Industry and Information Technology announced on Nov. 8 that the country will increase its rare-earth ore production to a record 132,000 tons this year in an effort to meet this demand.

But Samwood’s Kawasaki said China would need to import rare-earth metals from Myanmar and other countries as its own supply of rare-earth metals would not be enough in the medium- and long-term.